The headlight of a motorcycle is attached directly to the vehicle body. Thus, when the motorcycle banks at times such as turning, an illumination region illuminated with the headlight also tilts in the same way. The “turning” means changing the direction along a curved line. In cases of motorcycles, four-wheeled automobiles, etc., the “turning” means going around a curve. To “bank” means to tilt the vehicle body inward when the vehicle goes around a curve. Thus, when a motorcycle turns, the size of the visual field and the visibility decrease compared to those when the motorcycle travels in a straight line.
In recent years, there exist headlights of a light distribution variable type that change the headlight's light distribution depending on the bank of the vehicle body. The “light distribution” means luminosity distribution of a light source with respect to space. In other words, the “light distribution” means spatial distribution of light emitted from the light source.
At times of turning, the vehicle body travels like drawing a circle on the bank side of the vehicle body, and thus the line of vision of the driver is pointed toward a distant region on the inside of the corner where the vehicle body banks. The “bank side” means the direction in which the vehicle body tilts. The light distribution of the headlight needs to undergo not only correction regarding the tilt of the headlight due to the tilt of the vehicle body but also correction regarding the traveling direction of the vehicle body.
A headlight of the light distribution variable type described in Patent Reference 1 realizes both the correction regarding the tilt of the vehicle body and the correction regarding the change in the traveling direction at times such as the turning of a motorcycle. In the Patent Reference 1, a reflector is rotated around a longitudinal axis (X-axis) for the correction regarding the tilt of the vehicle body. For the correction regarding the change in the traveling direction, the reflector is rotated around an up-and-down axis (Z-axis). In short, in the Patent Reference 1, the entire light unit is rotated for the correction of the light distribution.